The method of spectral reflectometry and the device for its implementation were described by J. Ai and L. V. Wang in the paper <<Synchronous self-elimination of autocorrelation interference in Fourier-domain optical coherence tomography>>, Optics Letters, Vol. 30, No. 21, p. 2939-2941, 2005. The device comprises a broadband light source, an interferometer with a beam splitter in the sample arm, an interference control unit, a spectrometer, and a processing and visualization unit. The radiation from the broadband source is directed to the interferometer, part of the radiation scattered in the sample is withdrawn from the interferometer through the beam splitter and is directed to the spectrometer. The other part of the radiation scattered by the sample remains in the interferometer and is directed to the spectrometer only after being mixed with the reference part of the radiation. Both parts of the radiation are received by identical photoreceivers. Coherent noise is removed by measuring separate parts of the radiation. At the first stage, the total optical signal level is measured, for which the sample arm of the interferometer is blocked. At the second stage, the interference spectrum with coherent noises is measured. At the third stage, a spectrum without coherent noises is formed. The result is achieved by extracting from the interference spectrum with coherent noises the value of the total level of the optical signal. The drawback of the method and the device for its realization is a significant (up to four-fold) power loss of the radiation scattered by the sample due to takeoff of half of the power by the additional splitter on forward and backward passages. Besides, the interference control unit should be positioned immediately in the sample arm of the main interferometer, which greatly limits its area of applications.
The closest analog of the proposed method and device is the method and interference control unit described by R. A. Leitgeb, C. K. Hitzenberger, and A. F. Fercher in the paper <<Phase-shifting algorithm to achieve high-speed long-depth-range probing by frequency-domain optical coherence tomography>>, Optics Letters, Vol. 28, No. 22, p. 2201-2203, 2003. The device comprises a broadband radiation source, an interferometer containing an interference control unit represented by a modulator of phase between the reference and sample parts of the radiation, a spectrometer, and a processing and visualization unit. The radiation from the broadband source transmitted through the main interferometer has a definite phase difference between the reference and sample parts of the radiation. The interference spectrum of the reference and the sample parts of the radiation is received by an array of spectrometer photoelements. Simultaneous processing of several, successively received interference spectra with different phase shifts between the reference and the sample parts of radiation allows eliminating the influence of sample's self-interference on the final image. However, this method and device may be used only for investigation of sessile samples with slow internal motions that do not disturb phase relations as a result of the Doppler effect arising on the movable scatterers. Otherwise, there appear image artifacts.